1. Field of the Invention
The present invention relates to a construction of an IC card panel.
2. Description of the Related Art
FIG. 1 is a perspective view of a conventional IC card, while FIG. 2 is a sectional view taken along the line II--II of FIG. 1. Referring to these Figures, the conventional IC card 10 has a card body 1 with metallic upper panel 2a and a metallic lower panel 2b secured to the upper or obverse side and lower or reverse side of the card body 1, respectively. The card body 1 has an electric circuit board 4 supported in a frame 5 at about the middle of the thickness of the card, the circuit board 4 having semiconductor memory devices 3 as electronic components mounted on both major surfaces thereof. Referring specifically to FIG. 2, the circuit board 4 is supported by supporting steps (not shown) formed in the inner surfaces of the frame 5 and fixed thereto by means of, for example, an adhesive.
The upper and lower panels 2a and 2b fit on the upper and lower sides of the frame 5 so as to protect the internal parts including the semiconductor memory devices 3. More specifically, recesses for receiving the panels are formed along the peripheral edges of the upper and lower sides of the frame 5, and the panels 2a, 2b are received in these recesses and fixed to the frame 5 by, for example, an adhesive. Thus, the panels are secured without protruding beyond the surfaces of the frame 5. A plurality of electrode terminals 6 for exchange of signals between the semiconductor memory devices 3 and external devices are provided on one end of the frame 5. The frame 5 further has a bore 5a which extends in the direction of breadth of the frame 5. A potential equalizing spring 7 is mounted in the bore 5a so as to contact the upper panel 2a at its one end and the lower panel 2b at its other end.
The construction of the panels of the known IC card will be described in more detail. Referring to FIG. 1, the upper panel 2a and the lower panel 2b are fixed to the frame 5 by suitable means such as double-sided adhesive sheets or an adhesive agent. In order that the internal devices such as the semiconductor memory devices 3 inside the card body 1 have improved durability against electrostatic charges, it is necessary to keep the panels 2a and 2b at the same electrical potential, i.e., to keep them electrically connected to each other. This can be accomplished by the potential equalizing spring 7 which is received in the bore 5a formed in the frame 5 as explained before.
In the known IC card having the described construction, the upper and lower panels 2a and 2b are bonded only at small bonding areas, so that problems such as separation of the panels are often experienced due to insufficient bonding strength. In addition, the number of parts is increased and the assembly process is complicated due to the use of the potential equalizing spring 7 for maintaining electrical conduction between both panels 2a and 2b.